A virtual tape storage system (also referred to as a virtual tape library) is used to emulate an actual tape storage system. Many virtual tape storage systems are implemented as disk-based systems that contain virtual tape devices (implemented with disk-based devices) for emulating physical tape devices of the actual tape storage system.
A tape storage system is typically used for performing backup of data contained in various systems, such as application servers. However, tape storage systems are typically relatively slow, such that if the amount of data that has to be backed up is very large, then performing backups to tape storage systems becomes impractical. The use of virtual tape storage systems, containing disk-based devices, allows backup operations to complete in shorter amounts of time, since disk-based devices have higher access speeds than tape-based devices.
Virtual tape storage systems are associated with various issues. For example, each different application that requires tape resources also needs its own dedicated tape drive or even its own dedicated tape library. Thus sharing physical resources in a tape library can be difficult because a tape drive can only be used for one application at a time. This limited use of tape drives leads to inefficient use of tape drive resources. Drives reserved for one application can be idle while another application is unable to run because no drives are available.